Research On Spatio-Temporal Modelling, Updating And Representation Of Forest Subcompartment Data

The collection, management and updating data of sub-compartment, which is the basic unit of forest resources monitoring and statistics, the carrier of the forest resources in China, become more important in the era of the information techonology. There are much imperfection in these works because they are influenced by many factors, such as the study of the spatio-temporal course of subcompartment, the apply of information techonology and the improvement of the forest resources survey and monitoring. In actual work, There is lack of correlation between each phase of the data, the shape of the subcompartment is not maintained well and far different with the current state, therefore the data value is not fully realized and forestry department has to put emphasis on statistics.Spatio-temporal database, which research category includes spatio-temporal database modelling, spatio-temporal database updating, spatio-temporal indexing, and so on, is applied in many domains such as cadastral management and land utilization managment. It was introduced by this paper to express the spatio temporal course of sub-compartment.Based on a deep research of survey and monitoring work on forest resources, The paper analysised the spatio-temporal evolution of sub-compartment geo-entity and draw a conclusion that sub-compartment has a spatio-temporal course in which abrupt change and gradual change happen alternately. Therefore, a spatio-temporal expression method of sequence states based on the combination of snapshots and events was desingned to express spatio-temporal course in which abrupt change and gradual change happen alternately. The model, which was designed based on the method, express the spatio-temporal eveolution course of subcompartment by the combination of the scequeces of three kinds of object: subcompartment, subcompartment state and subplot states.The paper put forward a spatio-temporal data updaing framework which consists of spatio-temporal course, spatio-temporal model, data collection, updating mechanism and spatio-temporal database based on the study of forest resources data model. Updating mechnism realizes the database updaing based on the rule of space time consistency which is defined based on the integrity constraint defined in the data model. The paper deeply discussed the data sources available and the relation between them, every parts of the Updating mechanism, space time consistency and updating flow.The data squences in forest resources spatio-temporal database are the best expression to the sub-compartment spatio-temporal evolution. But the users usually only query the spatio-temporal squences in limited extent. The paper conveniently realize the reappearence of the state in the specific time and historial retrospect of the specific object based on event table, entity correlation table and time indexing table.Spatio-temporal expression should reach the user with visualization method that were not involved in the Previous spatio-temporal modelling study. Three spatio-temporal visualization method were designed in this paper, The first visualization method is history tree method in which sub-compartment, sub-compartment state, subplot state and their attributes is recorded in the tree nodes on different depths. The second method is vector feature evolution oriented space-time cube method in which three dimensions(x, y, t) are used to represent the evolution of area geographical entities such as subcompartment shape evolution, Multidimensional attribute evolution and so on. This paper also realize the dynamic representation of sub-compartment evolution.This paper realize every design mentioned above with a forest resources manage prototype system and its spatio-temporal database.With the development of the information technology, surveying and mapping technology, The method and technology of forest resources information management will also develop without stopping. This paper make a contribution to the development by a comprehensive study on modelling, updating and representation on sub-compartment data.